<?php

namespace DHTMLX\Connector\DataStorage;

use DHTMLX\Connector\Tools\LogMaster;

class MsSQLDBDataWrapper extends DBDataWrapper
{
    private $last_id = ""; //!< ID of previously inserted record
    private $insert_operation = false; //!< flag of insert operation
    private $start_from = false; //!< index of start position

    public function query($sql)
    {
        LogMaster::log($sql);
        $res = mssql_query($sql, $this->connection);
        if ($this->insert_operation) {
            $last = mssql_fetch_assoc($res);
            $this->last_id = $last["dhx_id"];
            mssql_free_result($res);
        }
        if ($this->start_from)
            mssql_data_seek($res, $this->start_from);
        return $res;
    }

    public function get_next($res)
    {
        return mssql_fetch_assoc($res);
    }

    public function get_new_id()
    {
        /*
        MSSQL doesn't support identity or auto-increment fields
        Insert SQL returns new ID value, which stored in last_id field
        */
        return $this->last_id;
    }

    protected function insert_query($data, $request)
    {
        $sql = parent::insert_query($data, $request);
        $this->insert_operation = true;
        return $sql . ";SELECT @@IDENTITY AS dhx_id";
    }

    protected function select_query($select, $from, $where, $sort, $start, $count)
    {
        if (!$from)
            return $select;

        $sql = "SELECT ";
        if ($count)
            $sql .= " TOP " . ($count + $start);
        $sql .= " " . $select . " FROM " . $from;
        if ($where) $sql .= " WHERE " . $where;
        if ($sort) $sql .= " ORDER BY " . $sort;
        if ($start && $count)
            $this->start_from = $start;
        else
            $this->start_from = false;
        return $sql;
    }

    public function escape($data)
    {
        /*
        there is no special escaping method for mssql - use common logic
        */
        return str_replace("'", "''", $data);
    }

    public function begin_transaction()
    {
        $this->query("BEGIN TRAN");
    }
}